c. 1950's. Just over 1/2" in diameter. In Britain, these very plain gold hoops were commonly called “sleepers” or “sleeper earrings.” They were designed to be left in continuously, including overnight, so a piercing wouldn’t close. They were often used as the first earrings put into newly pierced ears. British school rules have traditionally treated tiny studs or sleepers as the only acceptable earrings for schoolgirls. Adults wore/wear them too. Closes securely. The gold is a rosy yellow, somewhere between the two.